Hopefully nobody got too blue in the face waiting for this. A lot of data to go through, a busy schedule and other priorities... what can I say? Background: I installed a differential pressure test setup on my F150HD (5.4L 3V Modular V8). Mine is a two gauge setup with senders on either side of the filter. The gauges are Isspro stepper motor types... very accurate... and mounted in a one-wire-daisy-chain using Isspro's Performax system. The heart of the system is a CU which Isspro calls the ESP (Electronic Signal Processor). You can install up to 17 gauges on one wire with this system but, more importantly, it has a datalogging system (albeit a primitive one) that you can connect to a Windows laptop. I soiled my All-Mac-All-the-Time household by bringing in a used Windows laptop, which remains hidden when not in use. ( : < ) The one thing this setup does not datalog (though it could if I installed a sensor in the right place) is Engine Oil Temperature (EOT). I can monitor that another way, and datalog it too, but only in 2-3 minute intervals via an EFI programmer. Ditto for RPM and that is why you see these datapoints listed separately and sparsely. I went nuts trying to synchronize the two datalogs and finally resorted to good, old fashioned note-taking. While driving and operating the PC, I have to take note of the line number as the datalogger is recording and jot down the RPM or EOT at that moment. RPM is easy usually as I need only record the peaks or the steady state. EOT is ALL-IMPORTANT but since it rises and falls relatively slowly, it's easy to keep track of. The datalogger records four points per second, so even a short recording can yield dozen of pages of data... and it records all the data for which there is a sending unit. I cannot select which ones to record, so on a long record, I can have a hundred or so pages of data to sort thru because, 1) I can't post that much here, 2) you would go into a coma trying to sort thru it for the DP data, 3) you aren't interested in seeing what the rear diff temp or the fuel pressure at the time the DP is being tested. Viewing the Data: In reality, the P1 and MC Data comparison is not useful because of the viscosity disparity. That's why I did not get too anal over sorting out all that P1 Data. Things will get more interesting when I test other filters with the same oil. I am including the P1 stuff because it illustrates the effect oil viscosity has on DP. I plan to run another P1 with the 5W20 so we will see the differences. As mentioned above, the unit records four data points per second. I left the line number on for my own sanity and ability to see where I snipped that particular batch of data. Ditto for the time, which is also important for interpretation. After some experimentation and reflection, I have decided the important data was Engine Coolant Temp (ECT.. pay attention to the abbreviations), EOP-1 ( the inlet side of the filter), EOT-2 (the outlet side of the filter), EOT, RPM and Differential Pressure (DP) If I knew more about how to work Excel, I could probably set it up to make those DP calcs, but I am Excel-challenged and too busy to learn what I need to know. I did some of the calcs (simply subtract EOT-2 from EOT-1 to get the DP) at what I thought were the crucial points. You can do the subtraction yourself on any line where I didn't. Along the same lines, I added RPM only where I deemed it important from what I recorded in my notes. I picked what I thought was the most interesting parts of the data to present. Take it or leave it! ( : < ) The tests differ a little between these two tests here because I had not decided upon a test regiment for the first tests. They will match better from here on. The DP test regimen will be: 1) Cold start flare, 2) Cool oil WOT (Wide Open Throttle to about 5200 rpm with EOT~ 100F), 3) steady 55-60 mph cruise (1650-1750 rpm) at EOT=100F), 4) steady 55-60 mph cruise (1650-1750 rpm) at the highest oil temp that can be achieved reasonably (it will vary according to season), 5) Hot WOT at the highest oil temp achieved, 6) Hot idle at the highest oil temp that can be achieved. Remember to note the the time when viewing the data. When you find the point where the filter is in bypass, take note of the short durations thereof. Also take note that the bypass is not a full-open-or-full-shut event. The valve is calibrated to crack at X-psi and be fully open at Y. So if cracking is 8 psi, full open is 16 and DP is 8.8 the valve ain't opened much. Unfortunately, only a few mfrs. presents the opening pressure in a range, eg 8-16, which reflect the cracking and full open pressures. The other Mfrs usually only list one pressure, most often the full open pressure. I will list whatever pressure I have available. What is Differential Pressure?: Quite simply, it's the restriction of the filter media. It increases with viscosity and oil flow, so you will see it highest with cold oil, thick oil or with high rpm/oil flow. The Product Particulars: You will see the results of two oil/filter combos. The first is a Pure One (P1) #PL24651 combined with 10W30 Motorcraft Super Duty HDEO oil. Yes, that is more than a grade heavier than spec'ed for the truck... don't ask, it was an experiment. The DP setup was installed about halfway thru a 15K interval , in the 8K mile range, and I took some recordings then and again later at about 12K and the last right before the OC at a bit over 15K. The second set of Data came from a combo of an MC FL820s (generously donated by 2010FX4) and some stashed Castrol GTX SM 5W20 I had on hand. It had about a thousand miles on it for the tests. Conclusions: Few to make at this point. I can say that the Data from the early tests on the P1/10W30 combo were substantially the same as the last ones, so the suggestion is that filter loading had little effect on the tests. That makes sense since I have a bypass filter that is sharing the contaminant load. It's pretty easy to see the difference viscosity makes on cold starts. I won't pronounce on whether the filter efficiency (read restriction) or the oil viscosity has the most effect on DP until we see some Data on the more efficient filters with the 5W20, but my money is on the oil. P1/10W30 Cold Start Bypass Opening Pressure= 8-16 psi DP This was done in March of 2013 on a 37F morning. When the engine starts, it "flares" up to about 1700 rpm to "lite off" the cats and then settles into a high cold idle, gradually inching down as the engine warms. This is where the 10W30 oil really killed things. You can see how high DP pressure got (42 psi ( : < o) for a fraction of a second. It took around 12 seconds for the DP to stabilize below the cracking pressure. Remember that this is an extreme mismatch of cold oil (34 EOT... I didn't record it on my chart) where the oil viscosity is is more than a grade thicker than spec'ed. MC/5W20 Bypass Opening Pressure: 12.5-18.5 DP Efficiency: ~93%@20um This is the specified grade for the engine and the specified filter. Note that this combo did not exceed the bypass cracking DP. This is a combination of a much thinner oil with better cold start viscometrics and a medium efficiency filter with very little inherent restriction. P1/10W30 Cool WOT This is where I took a cool engine with EOT ~ 100F and revved it to the redline. I did some with a much colder engine and saw EOP over 100 psi. After a couple of those I saw no point in subjecting my engine to more of that. Wide open at 100F is bad enough. Only a moron or someone in fear for his life revs a stone cold engine to redline and the pitfalls are not important to the driver in either case and neither case applies to me. (I hope). Here is latest of the MC/10W30 at EOT=135F. You can see the DP only briefly rose above cracking pressure. I did another with EOT=64F and DP was 8.5-10 psi for about the same amount of time. Where is the MC/5W20 Cool WOT? Silly me! I lost that test somewhere in the bowels of my Windows laptop ( I despise XP). I will post it if and when I find it. I remember it though, and DP was well below cracking pressure the entire time. No drama. P1/10W30 Hot Wot This was done in the summer and at about 92F ambient. I was running at 200+ EOT, so even with 30 grade oil the DP was manageable. For some reason the DP and final RPM got clipped off so I will leave DP to you and your calculator. RPM was the same as all the other WOTs, ~5200. You can see I bumped past the bypass a couple of times very briefly (a second or so). This is rare with the oil hot, even with the 10W30 but I decided to show this segment to show you that it does happen. MC/5W20 Hot WOT It was only about 38F ambient so it took about 20 miles to reach 170F. It might have gone higher but... In any case, no drama. The thin oil and "loose" filter combined to offer low DP. DOn't start crowing about the MC filters just yet. In later installments, I will be using very high efficiency filters so we will see whether the oil viscosity or the filter is the major contributor of these low DP readings. MC/5W20 Hot Cruise Here is the MC and 5W20 in a hot cruise (1750 rpm) moment at EOT=171F. As you can see, no drama. Very low DP. I sorted similar data from the P1/10W30 Data but it comes thru here corrupted so I'll skip it for now. No drama there either. With roughly 15K on the oil and filter, in this situation DP is ~4.5 psi MC/5W20 Hot Idle ~EOT=171F No drama again. FYI, the P1/10W30 combo produced about 1+ psi more at idle.